I think this <code></code> and <p></p> parser would be harder to implement than it seems (even keeping in mind your counter points). [...] There is also the question of how do you parse out incorrect code/pseudo code.

Does that parser have to be complete and perfect? All we want at this point is a simple check that the raw posting text contains one or more <p> and zero or more <code> or <c> tags. (Tags, not elements. We don't even have to check for the closing tags. Existing code handles missing or mis-placed tags quite well.) Unless that condition is met, the poster will see a hint that (s)he should check is posting. Implementing those checks could be done using one or two simple regexps.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

What you describe already exists (try posting something in plain text to see). Anything more will require another layer that delays/prevents a post from being submitted so - yes, it would need to be a /very/ good parser. A parser that would be much more work than would be worth the trouble considering SoPW doesn't seem to get more than a total of 25 questions per day.

The handful of weekly "evil markup violators" can easily be handled with a quick private /msg with suggestions to improve their post. If they ignore it (which does happen), ignore the post and move on. ;-)

"...the adversities born of well-placed thoughts should be considered mercies rather than misfortunes." — Don Quixote

Ignoring the bad markup isn't a complete solution. Janitors still are likely to be asked to fix it.

As to posting plain text, I've never encountered difficulty including some... as in the case of the first (untagged) para in this node, nor in the case of a single sentence of narrative reply. (alternating paras with and without tags maintains readable rendering)

Re the quality needed -- As my update, above, illustrates, coding a set of simple tests for the most egregious failures can be done even by he who frequently wears a dunce cap and without writing anything like a complete parser. If one wished to be more rigorous -- to correct ALL flaws -- then one of the html parsers should make an easy starting point.

"Ignoring the bad markup isn't a complete solution. Janitors still are likely to be asked to fix it."

I wasn't offering it as a complete solution. I don't feel there is a complete solution and, as I've said, don't believe it would be worth the work for essentially a handful of weekly problematic posts. As for Janitors, that's part of their purpose:

What about crappily formatted postings?

...On the one hand, it could be left to the author to fix, and a /msg to the author is therefore the best course of action.

On the other hand, a janitor may feel that cleaning up a poorly formatted node, as a service to those who have to read such a node, and as a way of illustrating how nodes ought to be formatted, is reasonable.

And if the node's author is Anonymous Monk, it can't be fixed by the author, so if it's going to be fixed at all, it's got to
be done by janitors.
...

"As to posting plain text, I've never encountered difficulty including some... as in the case of the first (untagged) para in this node, nor in the case of a single sentence of narrative reply. (alternating paras with and without tags maintains readable rendering)"

What I posted was all plain text and got the following under the Title form field:

That was trying to post from my phone in all plain text. What you posted above is readable so I don't see a problem. Unless it brakes the page, I don't think we want to start parsing for totally valid html. That's not even a goal covered in the Janitor's doc and, as it suggests there, a private /msg to the OP can help remedy the situation. If it is a recurring problem from a specific poster suggest they change their setting to show markup errors. This is functionality which already exists but doesn't block a post from being submitted.

"...the adversities born of well-placed thoughts should be considered mercies rather than misfortunes." — Don Quixote

Went to join the gridlock to see it
Held an eclipse party
Watched a live feed
I cn"t see tge kwubosd to amswr thus
I tried to see it, but 8000 miles of rock got in the way
What eclipse?
Wanted to see it, but they wouldn't reschedule it
Read the book instead